Hey,
I'm a newbie. I want glow an array of 16 leds using a 4:16 decoder(Active Low)CD74HC154E Datasheet(PDF) - Texas Instruments. I'm using arduino Uno. But the 3mm white leds connected to the outputs of decoder are flickering. The typical voltage output is around 4v. I guess the problems may be due to low current driven by the decoder circuit.How to boost the current?
Is there any other way such as Led array drivers which I'm unaware of?
Thanks in advance!!
With a decoder you can only light one output at a time. You will have to switch addresses rapidly and repeatedly to give the appearance of more than one light on at a time.
Note that the decoder outputs are Active Low: All of the outputs are HIGH except the one selected. Connect your LEDs between output pins and +5V to get only one to light at a time.
You should also disable the outputs while you change the address pins to keep from lighting other LEDs. If you don't then as you change from 0b0000 (output 0) to 0b1111 (output 15) you are likely to light up 0b0001, 0b0011, and 0b0111 (1, 3, and 7) along the way. You can connect an output pin to either of the Enable pins and set that pin HIGH to disable the outputs.
Use two TPIC6B595 shift registers instead.
Shift in 2 bytes of data with the pattern you want.
No flickering, and capable of whatever drive current your LEDs need, vs the 4mA of the '154 part.